/* Copyright 2000-2008 MySQL AB, 2008 Sun Microsystems, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

/* Dynamic hashing of record with different key-length */

#ifndef _hash_h
#define _hash_h

#include "my_global.h"                          /* uchar */
#include "my_sys.h"                             /* DYNAMIC_ARRAY */

/*
  This forward declaration is used from C files where the real
  definition is included before.  Since C does not allow repeated
  typedef declarations, even when identical, the definition may not be
  repeated.
 */
#ifndef CHARSET_INFO_DEFINED
#define CHARSET_INFO_DEFINED
typedef struct charset_info_st CHARSET_INFO;
#endif  /* CHARSET_INFO_DEFINED */

#ifdef	__cplusplus
extern "C" {
#endif

    /*
      Overhead to store an element in hash
      Can be used to approximate memory consumption for a hash
     */
#define HASH_OVERHEAD (sizeof(char*)*2)

    /* flags for hash_init */
#define HASH_UNIQUE     1       /* hash_insert fails on duplicate key */

    typedef uint my_hash_value_type;
    typedef uchar *(*my_hash_get_key)(const uchar *, size_t*, my_bool);
    typedef void (*my_hash_free_key)(void *);

    typedef struct st_hash {
        size_t key_offset, key_length; /* Length of key if const length */
        size_t blength;
        ulong records;
        uint flags;
        DYNAMIC_ARRAY array; /* Place for hash_keys */
        my_hash_get_key get_key;
        void (*free)(void *);
        CHARSET_INFO *charset;
    } HASH;

    /* A search iterator state */
    typedef uint HASH_SEARCH_STATE;

#define my_hash_init(A,B,C,D,E,F,G,H) \
          _my_hash_init(A,0,B,C,D,E,F,G,H)
#define my_hash_init2(A,B,C,D,E,F,G,H,I) \
          _my_hash_init(A,B,C,D,E,F,G,H,I)
    my_bool _my_hash_init(HASH *hash, uint growth_size, CHARSET_INFO *charset,
            ulong default_array_elements, size_t key_offset,
            size_t key_length, my_hash_get_key get_key,
            void (*free_element)(void*),
            uint flags);
    void my_hash_free(HASH *tree);
    void my_hash_reset(HASH *hash);
    uchar *my_hash_element(HASH *hash, ulong idx);
    uchar *my_hash_search(const HASH *info, const uchar *key, size_t length);
    uchar *my_hash_search_using_hash_value(const HASH *info,
            my_hash_value_type hash_value,
            const uchar *key, size_t length);
    my_hash_value_type my_calc_hash(const HASH *info,
            const uchar *key, size_t length);
    uchar *my_hash_first(const HASH *info, const uchar *key, size_t length,
            HASH_SEARCH_STATE *state);
    uchar *my_hash_first_from_hash_value(const HASH *info,
            my_hash_value_type hash_value,
            const uchar *key,
            size_t length,
            HASH_SEARCH_STATE *state);
    uchar *my_hash_next(const HASH *info, const uchar *key, size_t length,
            HASH_SEARCH_STATE *state);
    my_bool my_hash_insert(HASH *info, const uchar *data);
    my_bool my_hash_delete(HASH *hash, uchar *record);
    my_bool my_hash_update(HASH *hash, uchar *record, uchar *old_key,
            size_t old_key_length);
    void my_hash_replace(HASH *hash, HASH_SEARCH_STATE *state, uchar *new_row);
    my_bool my_hash_check(HASH *hash); /* Only in debug library */

#define my_hash_clear(H) bzero((char*) (H), sizeof(*(H)))
#define my_hash_inited(H) ((H)->blength != 0)
#define my_hash_init_opt(A,B,C,D,E,F,G,H) \
          (!my_hash_inited(A) && _my_hash_init(A,0,B,C,D,E,F,G,H))

#ifdef	__cplusplus
}
#endif
#endif
